Process for printing superpolyamide



Patented May 29, 1951 "Princess Foit PRINTING snPERPoLyAMinE FIBERS WITH Latino-ESTER SALTS F VAT DYESTUFFS Fritz Reichartpliasel, and Karl Schlumpf, eu- Allschwil, Switzerland, assignors to Giba'Limited, Basel, Switzerland, a Swiss firm No Drawing. Application February 17, 1948, se-

rial No. 9,028. 1947 8 Claims.

It is known that the so-called fully synthetic fibers which may consist, for example, of superpolyamides or superpolyurethanes, and especially the textile fibersknown widely in commerce under the same nylon, possess dyeing properties different from those of any previously known fibrous materials. Although there is indeed a certain analogy between cellulose acetate artificial silk and nylon inasmuch as cellulose acetate artificial silk dyestuffs can generally be used for dyeing and printing nylon, there is great difficulty in dyeing and printing nylon with other classes of dyestuffs. Attempts to explain these differences systematically have not hitherto been successful.

The present invention is based on the observation that superpolyamide fibers can be printed in an advantageous manner by the use of leuco-ester salts of vat dyestufi's.

As superpolyamide fibers to be printed in accordance with this invention there come into consideration the known polycondensation products of dicarboxylic acids with diamines or the autocondensates of amino-w-carboxylic acids. The fibers can be subjected to the process of the invention in any desired state of manufacture, but especially in the form of woven or knitted goods. An advantage of the invention is that no special pretreatment of the goods to be printed is necessary. However, in some cases a certain cleansing treatment,.for example, desizing, defatting or like treatment, may be of advantage.

As leuco-ester salts of vat dyestuffs there may be used, more especially, the generally known alkali salts of sulfuric acid leucoesters of vat dyestufis. They, may be derived from vat dyestuffs of the indigoid, mixed indolethioindigoid or pure thioindigoid series, or from vat dyestuffs of the anthraquinone series. products may be used directly in the process of the invention.

The printing process is advantageously carried out by printing the goods with a printing preparation containing, in addition to the ester salt, a customary thickening agent and certain added substances, then drying the printed goods and steaming them in the normal manner. After steaming, the color is in some cases fully de- The commercial- In Switzerland February 21,

with a soaping operation. In some cases, especially when the steaming is of short duration, an improvement in the fixation and/or development of the dye can be obtained by an-aftertreatment with an acid oxidizing agent, for example, in a bath containing sulfuric acid and sodium nitrite.

The printing preparations used in the present process may contain as a thickening agent, for example, an ordinary starch-tragacanth thickening, in which" the relative proportions of the tragacanth mucilage and starch paste may vary within the usual limits according to requirements. These thickenings mayalso contain other additions.

Printing preparations, which are designed to form a vat dyestuff from a leuco-ester salt of a vat dyestuff during steaming" without any oxidizing after-treatment, normally contain an agent capable of liberating acid, which agent produces the acid reaction necessary for oxidation only under the conditions of steaming, and also an oxidizing agent which is capable of oxidizing the leuco-compound to the vat dyestuif under the same conditions. As agents capable of liberating acid there come into consideration for the present process more especially, ammonium salts of relatively strong acids, particularly ammonium sulfate and advantageously ammonium thiccyanate. As oxidizing agents there may be used in the present process chlorates, for example, sodium or ammonium chlorate, and also nitrates and similar known oxidizing compounds.

Especially good results are obtained b'y'the present process by using organic nitro-compounds instead of or in addition to the usual oxidizing agents. It is of advantage to use nitro-compounds which are soluble in aqueous printing preparations. This is the case especially with organic nitro-compounds which contain in an aromatic nucleus, in addition to one or more nitro groups, at least one group imparting solubility, for example, a carboxylic acid or sulfonic acid group. In many cases it has proved to be of advantage'to use the easily accessible metanitrobenzene sulfonic acid. Such nitro-compounds are advantageously incorporated in the printing preparation "in the form of their water-soluble salts, for example, their sodium salts.

It is surprisin that the "en fir mm. a.

compounds renders unnecessary the addition of the otherwise usual catalysts, such as ammonium vanadate or a ferricyanide or ferrocyanide, and this represents a further simplification of the process and leads to greater stability of the printing preparations. Instead of localized prints, uniform dyeings can be produced by padding or foularding onto the goods, as a normal printing paste, a paste which is suitably somewhat less thickened, and proceeding in the usual manner in all other respects.

The prints and dyeings obtainable by the invention possess good properties of fastness and can be produced in a simple manner.

The following examples illustrate the invention, the parts being by weight:

Example 1 A nylon fabric, which has not been pretreated, or which has been slightly washed, is printed with a printing preparation of the following composition:

Parts The sodium salt of the sulfuric acid ester of The printed material is then dried in the usual manner, and steamed for hour in a star frame steamer under slightly superatmospheric pressure (about 1 /4 atmospheres). The goods are then rinsed, soaped at the boil, and again rinsed hot and then cold. The following tints are obtained depending on the vat dyestufi from which the ester salt is derived:

(1) 4 :4=-dimethyl-6 :6 -dichloro -thioindigo pink (2) 4 :7 -dimethyl-6 6' -dichloro-thioindigo pink (3) Dichloroisodibenzanthrone violet (4) 4 5-benzo-5-methyl-6' -chlorothioindigo bordeaux Steaming can be extended to one hour or shortened, for example, by carrying it out in a Mather-Flatt ager. The latter treatment is appropriately followed by the acid nitrite treatment described in Example 2.

Example 2 A nylon fabric, which has been lightly cleansed, is printed with the following printing preparation:

Parts The sodium salt of the sulfuric acid ester of leuco-dimethoxy-dibenzanthrone 80 fl:/3-dihydr0xydiethyl sulfide 40 Water 2'70 Starch-tragacanth thickening 500 Ammonium thiocyanate solution 1:1 100 Sodium meta-nitrobenzene sulfonate The printed material is dried and steamed for 30 minutes in a star frame steamer, then rinsed and after-treated at 60-70" C. in an acid nitrite bath containing, per liter of water, 2 grams of sodium nitrite and 36 grams of sulfuric acid of 94 per cent. strength. There is obtained a brilliant green print.

Example 3 throne (green) 10 fl:B-dihydroxydiethyl sulfide 20 Tragacanth thickening 200 Ammonium thiocyanate solution 1:1 Sodium meta-nitrobenzenesulfonate 10 Water 660 The fabric is dried and finished as indicated in Example 2. Even dyeings in the shades indicated under (a), (b), and (0) above are obtained.

A blotch roller may be used instead of the foulard.

It is to be understood that the art of printing is still highly empirical and according to the particular brand of fibers to be printed, the steaming and printing apparatus available, etc., alterations in the recipes can be made without departing from the spirit of the invention. Thus, for example, other oxidizing agents can be added, such as sodium or ammonium nitrate or chlorate, the sodium salt of meta-nitrobenzene sulfonic acid may in part or wholly be replaced by other salts, including the ammonium salt. While the meta-nitrobenzene sulfonates have been chosen in view of their low cost, isomers thereof or the corresponding carboxylic acid salts may be used.

Having thus described the invention, What is claimed is:

1. In a process for printing superpolyamide fibers with a leuco-ester salt of a vat dyestuii, the steps of printing the said fibers with a printing paste which contains the said leuco-ester salt, an agent which liberates acid in the heat, and, as sole oxidizing agent, a water-soluble salt of a nitrobenzene sulfonic acid free from other substituents.

2. In a process for printing superpolyamide fibers with a leuco-ester salt of a vat dyestuff, the steps of printing the said fibers with a printing paste which contains the said leuco-ester salt, an ammonium salt of a strong acid, and, as sole oxidizing agent, an alkali metal salt of metanitrobenzene sulfonic acid, and steaming the printed fibers whereby the dyestuff is fixed and the greater part thereof is simultaneously developed Without addition of any other oxidizing agent.

3. In a process for printing superpolyamide fibers with a leuco-ester salt of a vat dyestuff, the steps of printing the said fibers with a printing paste which contains the said leuco-ester salt, ammonium thiocyanate, and, as sole oxidizing agent, the sodium salt of meta-nitrobenzene sulionic acid, and steaming the printed fibers whereby the dyestufi is fixed and the greater part thereof is simultaneously developed without addition of any other oxidizing agent.

4. In a process for printing superpolyamide fibers with a leuco-ester salt of a vat dyestuif, the

steps of printing the said fibers with a printing paste which contains the said leuco-ester salt, ammonium thiocyanate, and, as sole oxidizing agent, the sodium salt of meta-nitrobenzene sulfonic acid, and steaming the printed fibers whereby the dyestuff is fixed and the greater part thereof is simultaneously developed without addition of any other oxidizing agent.

5. A printing paste suitable for printing superpolyamide fibers with a leuco-ester salt of a vat dyestuff, which contains the said leuco-ester salt,

} an agent which liberates acid in the heat, and, as

sole oxidizing agent, a water-soluble salt of a nitrobenzene sulfonic acid free from other substituents.

6. A printing paste suitable for printing superpolyamide fibers with a leuco-ester salt of a vat dyestufi, which contains the said leuco-ester salt, an ammonium salt of a strong acid, and, as sole oxidizing agent, an alkali metal salt of meta-nitrobenzene sulfonic acid.

7. A printing paste suitable for printing superpolyamide fibers with a leuco-ester salt of a vat dyestufi, which contains the said leuco-ester salt, ammonium thiocyanate, and, as sole oxidizing agent, the sodium salt of meta-nitrobenzene sulfonic acid.

8. A printing paste suitable for printing su perpolyamide fibers with a leuco-ester salt of a vat dyestufi, which contains the said leuco-ester salt, ammonium thiocyanate, and, as sole oxidizing agent, the sodium salt of meta-nitrobenzene sulfonic acid.

FRITZ REICHART. 

5. A PRINTING PASTE SUITABLE FOR PRINTING SUPERPOLYAMIDE FIBERS WITH A LEUCO-ESTER SALT OF A VAT DYESTUFF, WHICH CONTAINS THE SAID LEUCO-ESTER SALT, AN AGENT WHICH LIBERATES ACID IN THE HEAT, AND, AS SOLE OXIDIZING AGENT, A WATER-SOLUBLE SALT OF A NITROBENZENE SULFONIC ACID FREE FROM OTHER SUBSTITUENTS. 